FLIES. 



433 



Fig. 546. — Ol/ersia, bird-tick, enlarged. 



In the Pupipara there are not many more than one hundred species known, but 



they are among the most curious in the whole order. The eggs are hatched and the 



larval stage passed within the body of the 



parent, and are extruded by the parent only 



when they are nearly ready to become pupae. 



As one would suppose, the flies are not at all 



prolific, only a single one is brought forth at 



a time. The head is closely connected with 



the thorax, in the wingless forms largely con- 

 cealed ; the proboscis is firm and adapted for 



piercing, the legs are stout and provided with 



strong denticulated claws; the veins of the 



wings are present only in front, or at least the 



posterior ones are rudimentary. The flies are wholly parasitic 

 upon birds and mammals, moving about very quickly among the 

 feathers and hair. A common species is Olfersia americana, 

 found on several species of birds, such as the Virginia horned 

 owl, several hawks, ruffed grouse, etc. ; it has a smooth, horny, 

 flattened, yellowish bod)'. The genus Lipoptena is remarkable in 

 that in the earlier state the flies have wings and live on birds, 

 but later they seek quadrupeds, where they remain, and having 

 no further use for their wings, they lose them. Hippobosca (from 

 which this family, Hippoboscid^, takes its name) equina, is a 



winged species that lives on the horse. The sheep-tick, Melophagus, 



is wingless. Usually not many individuals infest a single animal, 

 but instances have been known where more 

 than a hundred specimens have been found on 

 a single swallow. 



The Ntcteeieid^ are only found on bats. 

 They are very remarkable, wingless, spider-like 

 insects, with a very small head and the eyes 

 either small or wholly wanting. They are small, 

 rarely more than a sixth of an inch in length. 



The family Beaulid^ comprises only a single minute species, 

 not two millimeters in length. The head is large, wholly with- 

 out eyes, the thorax small and without wings, and the legs are 

 short and stout, with strong pectinated claws. These degraded 

 flies are parasitic upon honey-bees, especially the drones, living 



among the hair of the thorax ; they are called bee-lice. 



S. W. WlLLISTON. 



Fig. B47 . — Hippobosca 

 equina. 



Fig. 548. — Melopha- 

 gus ovinus, slieep- 

 tick, enlarged. 



Fig. 549. — Nycteribia 

 westwoodi, bat-tick, 

 enlarged. 



